Aromatic polyol cross-linked thermoset resin compositions



United States Patent 3,336,259 AROMATIC POLYOL CROSS-LINKED THERMOSET RESIN COMPOSITIONS Robert L. Zimmerman and Willard E. Alexander, Midland, MiclL, assignors to The Dow Chemical Company,

Midland, Mich., a corporation of Delaware N0 Drawing. Filed Feb. 5, 1964, Ser. No. 342,789

8 Claims. (Cl. 260-47) This invention relates to thermoset resin compositions comprising a homogeneous copolymer of a monovinylidene aromatic compound and an e -unsaturated cyclic anhydride and an aromatic hydroxyl containing curing agent.

The invention further relates to heat-converted protective and decorative coatings, laminates and moldings of the thermosetting compositions for machines, house hold appliances, automotive equipment, tools, metal panels and the like and to articles coated with a cured coating of the thermoset resin compositions.

Vinylidene aromatic compounds which are suitable include, for example, styrene, vinyltoluene, t-butyl styrene, ar-monoor di-chlorostyrene, a-methylstyrene, vinylxylene and the like.

a a-Unsaturated dicarboxylic anhydrides which are suitable include, for example, maleic anhydride, chloromaleic anhydride, dichloromaleic anhydride, citraconic anhydride, itaconic anhydride, phenyl maleic anhydride and aconitic anhydride.

The copolymer employed in this invention advantageously contains from to 40 mole percent, preferably 5 to 15 mole percent, of the cyclic anhydride and correspondingly from 95 to 60 or 95 to 85 mole percent of the monovinylidene aromatic monomer. The invention includes partially esterfied copolymers which 'can be esterified up to about 80 percent, wherein 200 percent denotes complete esterification with a monoalcohol.

Polymers having a solution viscosity of no more than cps. (10 percent in methyl ethyl ketone) at 25 C. are advantageously employed. The preferred polymers have a viscosity of 0.5 to 1.7 cps. Most advantageously the polymers are of homogeneous composition, that is, the cyclic anhydride content of at least 90 weight percent of the polymer is within a 5 weight percent range, most desirably within a 2 weight percent range as determined by fractional precipitation analysis.

The polyol is advantageously an aromatic compound with two or more hydroxyl groups, at least one of which is nonphenolic and in which the ratio of aliphatic to aromatic carbons is not greater than 3:2. Representative polyols are p-xylylene glycol, dihydroxymethyl diphenyl oxide, dimethylol phenol, alkylene oxide adducts of polyphenols such as Bisphenol A and hydroquinone, polyacid/ polyol polyesters with terminal OH groups, and the like. Optionally, aliphatic polyols and other reactive ingredients such as organic monoalcohols, amines, mercaptans, and acids may be coreacted in the thermosetting formulations, as well as other thermosettingingredients such as formaldehyde resins.

The compositions of this invention containing the aromatic polyols have improved heat distortion and exhibit better heat resistance with respect to similar com positions cured with aliphatic polyols. The aromatic polyols also have improved compatibility with the base copolymers both in solution and in the dried state. The improved compatibility results in better strength in products such as preimpregnated paper.

The composition of this invention advantageously comprises from 3 to.50 weight percent of the polyol, prefer ably from 5 to 25 weight percent. For best results the ratio of hydroxyl to anhydride should fallwithin the range of 0.3 to 1.5

The combination of a low molecular weight copolymer and a relatively large amount of the polyol additive provide impregnating solutions of high solids. Solutions of 50 percent solids or greater have practical working viscosities.

The mixture of resinous copolymer and curing agent can be in solution in an organic solvent, or, for high anhydride polymers, can be dissolved in an aqueous base. The mixture can also be dry, as cast from a solution or a fine dry blend of the ingredients. The product mixture is reactive and may cure at ambient temperature, although A styrene copolymer of 1.28 cps. viscosity containing 10.25 weight percent maleic anhydride prepared by the method of Ser. No. 33,376, filed June 2, 1960, was mixed with a series of aromatic polyols on a two-roll mill at 160180 C. (The polyol was added in a ratio of 1.5

hydroxyl groups per anhydride group.) The resulting partially cured mixture was ground, then compression molded for /2 hour at 350 F. into an %'T thick chip. Heat distortion temperatures of the chips were measured on a modified Vicat apparatus similar to that described in ASTM designation D-152558T. Extent of crosslinking was determined as that portion of the cured chip which was insoluble in methyl ethyl ketone. Approximately one gram of the sample was weighed and soaked for 48 hours at room temperature in methyl ethyl ketone (MEK),

after which the undissolved portion was collected, dried,

and weighed. The results are given in the following table.

TABLE I OH Curing Heat Percent Curing Agent Eq. Agent, Distortion Insoluble Wt. Weight (Vicat), C. in MEK Percent 2,6-dimethylol-4-methyl phen 83 7. 98 114. 9 80. 7 p-Xylylene glycol 69 9. 78 95. 4 99. 3 Ethylene oxide adduct f Bisphenol A- 158 19. 9 86.1 84. 2 Oxy-bis-benzyl alcohol-pp 16. 4 106.8 98. 6 Di(ethylene glycol) tetrabromophthalate 285 30.9 90. 4 67. 7 Di(diethanolamine) phthalate 78 10. 9 119. 2 95. 0 Propylene oxide adduct of Bisphenol A 172 21. 2 72. 4 45. 8 Di(hydroxymethyl) diphenyl oxide 1 126 16. 4 76. 6 96. 7

1 Prepared by hydrolysis of ehloromethylated diphenyl oxide mixed isomers.

Example 2 Samples for Table II were prepared by mixing the indicated amount of aromatic curing agent in 50 percent acetone (to provide 1.5 hydroxyl groups per anhydride group), to a solution containing 50 weight percent of a The unimpregnated paper had a tensile strength of 1980" p.s.i. Tensile strengths of the dried impregnated paper are 3 shown. Another portion of said solution was catalyzed with 0.5 percent DMP-30 [tri(dimethylaminomethyl)- phenol] based on resin solids and heated to 400 F. in an open dish for one hour, during which time the acetone of the solvent and unpolymerized monomers to recover the resin the half ester partially reverted to maleic anhydride. The resins were analyzed by titration of hydrolyzed and anhydrous samples to determine the relative volatilized and the sample cured. The MEK insoluble portion was measured as in Example 1. proportions of half ester and anhydnde.

TABLE II Uncured Dry Resin Curing (0.5% DMP) Curing Compatibility of Agent percent MEK Curing Agent A genltt, 52%Iesi114C12rlng 161501. 1 e21 111 CG 0118 GD Pei cgnt g Appearance Paper Pre-Prcg. Tes t 400 lei/1 Tensile, p.s.i. hr.

Propylene oxide adduct of BisphenolA 21.2 Compatible Compatible..- 3,145 81.8 Di(hydroxylmetl1yl) diplienyl oxide 16.4 do do 3,694 91.2

Example? 20 The cured samples were clear, hard and essentially Styrene/maleic anhydride copolymer, 10 g., and Dow insoluble in MEK.

TABLE IV Mole, Ester- Wt. Percent percent Mole, Mole, ifica- Vlsc., Curing Curing Arquad i AM percent MA percents tion cps. AGgent, Agent 12-50 cc.

3. 53 e. 1 90. 4 5s 4. 2 1. 425 0. 0s 6. 75 11. 2 s2. 1 5s 2. s 2. 60 20. 7 0. 0s 7. 05 1. 94 91 4G 2. 7 3.69 27. 0 0. 09

Resin 565 [propylene oxide adduct of Bisphenol A (OH Example 5 l' 5 E g z f g i A The fiberglass laminates shown in Table V were made ca a Y rqua O ecy nme y ammomum by stacking 12 plies of impregnated style 181 glass cloth chllonde g m lsopropfylhalcolllol) was added having a Volan A finish and curing in a compression vo umetrica an a ortion o t e so ution cast in an 3 aluminum m isture dish After dr in overni ht the cast Press for hour at 350 and 360 preSsur-e The 1 b k d t 1, O f y i i d lmpregnatlng solutions contamed 40 percent by weight of samp e was a e a or one our an resin solids in acetone, the resin solids consisting of a .(See Table Clarity Cure as miaasured by msolublhty 1.42 centipoise styrene/ 10.25 percent maleic anhydride m and hardness were good m all cases copolymer admixed with the curing agent (calculated to TABLE III provide 1.5 hydroxyl groups per anhydride group). As

catalyst, 0.5 weight percent of DMP-30 [tri(dimethyls/MA Resin Wt aminomethyl)phenol] was added immediately before imgurin g lerurcierrlt A gqggd pregnation. The cloth was coated with this resin solution en Wt. Percent Mole, Vise, cps. G ms. Agent cc. then a1 r-dr1ed for about 24 hours to remove the acetone. A Percent The dned preimpregnated cloth contalned about 45 percent resin. ggg 3.? 3 322 3.3 38; The polyester curing agents shown in the table were i313 313 2:; 313% 3:2 3:83 gadded as follows: (11k) EGA:-te;rabromop1hthalfic any n e was prepare y reacting gm. mo es 0 tetra- $2 52;? 1 2:2 $21; 8:18 bromophthalic anhydride with 6 gm. moles of ethylene glycol (plus 20 percent excess) in the presence of grns. xylene, at reflux until an acid number of 39.0 mg Example 4 35 KOH per gram resin had been obtained. PAGLNo. 5

The procedure of Example 3 was followed using 10 g. samples of partial esters of styrene/maleic anhydride. These resins were prepared by the continuous polymerizaand No. 6 were prepared by reacting phthalic anhydride (1 mole), glycerine (1 mole), and lauric acid (0.4 mole) in the presence of refluxing xylene until the acid number was 30.9 for No. 5 and 17.7 mg. KOH per gram resin for tion method of Ser. No. 33,376, filed June 2, 1960, using 40 No. 6.

TABLE V.-PROPERTIES OF POLYOL GURED THERMOSETTING LAMINATE Wt. percent Laminate Wt. Gain Tensile Laminate Curing Agent OH Equiv. oi Curing Thickness 2 Hr. H20

o. Wt. Agent (inches) Boil g g & v

Dlhydroxy methyl DPO. 126 16. 46 0. 137 0. 14 55, 000/2. 24 Oxy-bis-benzyl alcohol. 16. 42 0.139 0. 181 56, 000/2. 06 EGA tetrabromophthalic 211111.. 285 30. 96 0. 099 1. 68 35, 000/3. 24 PAGL, No. 5 412 46. 10 0. 093 2. 61 34, 000/3. 07 PAGL, N0. 6 455 41. 78 0. 094 3. 73 32, 000/2. 80

a monomeric feed consisting of styrene, isooctyl acid We claim:

maleate and methyl ethyl ketone. Upon devolatilization 1. Composition comprising a copolymer of a monothe ratio of aliphatic to aromatic carbons is not greater 5 than 3:2.

2. Composition of claim 1 wherein the copolymer contains from 5 to 40 mole percent of the cyclic anhydride.

3. Composition of claim 1 wherein the copolymer contains from 5 to 15 mole percent of the cyclic anhydride.

4. Composition of claim 1 wherein the polyol comprises from 3 to 50 weight percent of the total mixture.

5. Composition of claim 1 wherein the aromatic compound is styrene.

6. Composition of claim 1 wherein the cyclic anhyoride is maleic anhydride.

7. Composition of claim 1 wherein the polyol is a member of the group consisting of 2,6-dimetl1ylol-4- methyl phenol, oxy-bis-p,p'-benzyl alcohol and di(diethanolamine phthalate.

8. Composition of claim 1 wherein the ratio of hydroxyl to anhydride is from 0.3 to 1.5.

References Cited UNITED STATES PATENTS 10 2,912,413 11/1959 Baer 260-75 OTHER REFERENCES 5 WILLIAM H. SHORT, Primary Examiner.

M. GOLDSTEIN, Assistant Examiner. 

1. COMPOSITION COMPRISING A COPOLYMER OF A MONOVINYLIDENE AROMATIC COMPOUND OF THE BENZENE SERIES AND AN A,B-UNSTAURATED CYCLIC ANHYDRIDE, AND AN AROMATIC POLYOL CURING AGENT CONTAINING TWO OR MORE HYDROXYL GROUPS, AT LEAST ONE OF WHICH IS NONPHENOLIC AND IN WHICH THE RATIO OF ALIPHATIC TO AROMATIC CARBONS IS NOT GREATER THAN 3:2. 